Agilent Technologies U1253B User's And Service Manual page 176

6 Performance Tests and Calibration
The accuracy of 500 Ω and 5 kΩ is specified after the Null function.
[3]
[4]
For the range of 50 MΩ/500 MΩ, the relative humidity is specified for < 60%.
[5]
The accuracy is specified for < 50 nS, with the Null function performed on open test leads.
[6]
All frequency counters are susceptible to error when measuring low-voltage, low-frequency signals. Shielding inputs from
external noise pickup is critical for minimizing measurement errors.
[7]
Use the Null function to offset for residuals.
[8]
The accuracy does not include the tolerance of thermocouple probes. The thermal sensor plugged into the multimeter
should be placed in the operating environment for at least an hour.
[9]
Always use the relative function to zero the thermal effect with open test leads before measuring the signal. If you do not
use the relative function, add 20 digits to the error.
[10]
10 A continuous, and additional 0.5% error to specified accuracy when measuring a signal greater than 10 A to 20 A for 30
seconds maximum. After measuring a current of > 10 A, cool down the multimeter for twice the measuring time you applied
before performing a low current measurement.
[11]
The current can be measured from 2.5 A to 10 A continuous, with an additional 0.5% error to specified accuracy when
measuring a signal greater than 10 A to 20 A for 30 seconds maximum. After measuring a current of > 10 A, cool down the
multimeter for twice the measuring time you applied before performing a low current measurement.
[12]
For signal frequencies greater than 1 kHz, an additional 0.1% error per kHz needs to be added to the accuracy.
150 U1253B User's and Service Guide